THOUSAND OAKS, Calif. — Nicolina Ranieri, a senior at California Lutheran University, sorts through her clothes in a dormitory laundry room.

Ranieri pays careful attention to the labels and reads the tag on a green hoodie.

“We’ve got 60% polyester and 40% cotton,” Ranieri said.

After she tosses it into the washer, she grabs another garment.

“This is 50% cotton and 50% polyester,” she said.

Ranieri is fascinated with what comes out in the wash — and then into the ocean.

An hour later, that’s where she and classmate Domonic Berger were — 26 miles away at Sycamore Cove beach. They tiptoed into the surf to gather sand crabs. They will haul them back to class in a cooler, where they and other students dissect sea life to look for the tiniest bits of synthetic fiber. 

“And I had no idea they came from washing your clothes,” Ranieri said.

Back in the lab, Berger — now dressed in a lab coat — peeped through a microscope at a tissue sample from an oyster. A colorful thread popped up on a digital screen.

“That one is a blue microfiber,” Berger said.

It was most likely a remnant from someone’s clothing, he added.

Ranieri and Berger are part of a biology class at Cal Lutheran that’s conducting ongoing research on the connection between synthetic clothing and microfiber pollution in the oceans.

Dr. Andrea Huvard, a biology professor, is their instructor. And Huvard also leads her students on a scientific “who-done-it” that began in the last century.

“OK, so here we are, back in the 1950s,” Huvard explained. “You know, plastic gives us better living.”

Huvard is speaking to the time during and after World War II, when humans one-upped mother nature’s cotton to produce so-called “man-made fibers,” more durable and flexible threads like nylon, rayon and polyester, which are essentially plastics made from petroleum products. 

Huvard noted that today, more than half of our collective wardrobe in the United States is 75-100% synthetic. She explained how when we put our clothes through the wash, these fibers shed. 

“Every time we wash a fleece jacket, about 800,000 individual microfibers are shed from that one garment,” Huvard said. 

Cotton also sheds. But unlike cotton fibers that are biodegradable, Huvard said, synthetic fibers end up in the “grey water” that is poured into our sewage system.

“And the filters that are in water treatments plant aren’t fine enough to catch all of these fibers,” Huvard said.

So, the synthetic fibers then float into a watershed, which eventually leads to the ocean where sea life — our seafood — absorb them.

Mountains of data gathered in Huvard’s years-long study suggests microscopic threads are inextricably interwoven into our food supply. Very rarely do her students not find microfibers in a tissue sample. They not only find synthetic clothing fibers in sediment and sand crab samples taken from local California beaches, but they also find them in seafood purchased from local markets, like squid and oysters.

In the lab, Julia Bures shucked a store-bought oyster to prepare it for analysis. She said sea life ingests the microfibers, but they do not expel them. Bits of the tiny fibers, shorter than five millimeters, remain in the flesh.

“No matter how long you cook it, you’re still going to be eating it,” Bures said.

Huvard said the fibers themselves are not harmful to humans. However, the fibers effectively act like sponges, absorbing other pollutants in sea water, which humans, in turn, ingest into their bodies. 

Huvard said it’s worth noting how all her students are undergrads who are doing what is equivalent to doctoral research.  Their work has already been published in scientific journals.

Huvard admits that microfibers are beneficial. They have allowed humans to stay warmer, or cooler, or dryer than cotton fabrics would allow. 

That’s the reason, Huvard said, microfibers are here to stay. But she added that humans can cut down on pollution by limiting the number of times we wash our clothes. Or we can make better choices. 

“Maybe I only need two fleece jackets, not 10,” Huvard said. 

But Huvard said the real benefit is giving her students perspective and agency. 

“The future is really in their hands. They’re going to have to decide what kind of environment they want to live in,” she said.

That’s why Ranieri said she takes constant inventory of her clothes in the laundry room. She pulled a T-shirt out of the pile.

“This is 100% cotton, actually, which is good,” she said. “No microfibers.”

“I definitely have taken steps to minimize my doing in polluting the ocean,” Ranieri added.